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University of Colorado, Boulder

Dispersion

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Lamb Waves With Conical Dispersion At Zero Wavenumber, David M. Stobbe Jan 2018

Lamb Waves With Conical Dispersion At Zero Wavenumber, David M. Stobbe

Mechanical Engineering Graduate Theses & Dissertations

Lamb waves are guided elastic waves in plates. These waves are dispersive, with the frequency and wavenumber related by the well-known Rayleigh-Lamb equation. Generally, at zero wavenumber the dispersion curves are parabolic and the waves are non-propagating thickness resonances. For distinct values of Poisson’s ratio, however, degeneracy can occur between thickness resonance modes. At these coincidence frequencies the dispersion curves become linear and in a three-dimensional representation the dispersion surface is shaped like a cone. This behavior is referred to as conical dispersion. Waves excited at coincidence frequencies maintain the infinite phase velocity associated with thickness resonances but transport ...